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    Archived pages: 368 . Archive date: 2013-08.

  • Title: Milky Way Galaxy Map
    Descriptive info: .. map.. |.. book.. blog.. gallery.. webcards.. sources.. Galaxy Map brings together the latest scientific results mapping our home galaxy, the Milky Way.. If you are new to this site, you may want to start with the section on the.. basic plan of the Milky Way.. and take a look at some of the other chapters in.. Our Galactic Region.. This is not only a guide to the maps on this site and how they were constructed, but includes a growing amount of information about the key scientists mapping the Milky Way and some of their most exciting discoveries.. If you would like to learn about the latest developments, read the.. Galaxy Map blog.. or follow the.. Galaxy Map twitter feed.. There are two sets of Milky Way maps available on this site:.. a Google maps interface, the.. Milky Way Explorer.. , showing what our galaxy would like if we had the eyes to perceive the sky at infrared, microwave and radio frequencies, and.. a.. face-on set of maps.. showing what our galaxy might look like from an interstellar spaceship, including the distances and positions of more than 8 thousand bright stars, star clusters, nebulae and giant molecular clouds.. Images, descriptions, and references to the scientific literature are available for many objects, containing a vast amount of information on objects found within about 10 thousand parsecs (some 30 thousand light years) from our Sun.. The site includes guides to the.. Sharpless.. ,.. Gum.. RCW.. nebulae.. These deep sky objects are now within the reach of many CCD-equipped amateur telescopes.. In addition to maps and images, there is the beginning of a guide to the Milky Way:.. as well as first drafts of a.. Commentary on the Galactic Plane.. and a commentary on.. the whole sky as seen in hydrogen-alpha.. , the frequency of  ...   Government grant NAG W-2166.. The images of these surveys are based on photographic data obtained using the Oschin Schmidt Telescope on Palomar Mountain and the UK Schmidt Telescope.. The plates were processed into the present compressed digital form with the permission of these institutions.. The Second Palomar Observatory Sky Survey (POSS-II) was made by the California Institute of Technology with funds from the National Science Foundation, the National Geographic Society, the Sloan Foundation, the Samuel Oschin Foundation, and the Eastman Kodak Corporation.. The UK Schmidt Telescope was operated by the Royal Observatory Edinburgh, with funding from the UK Science and Engineering Research Council (later the UK Particle Physics and Astronomy Research Council), until 1988 June, and thereafter by the Anglo-Australian Observatory.. The blue plates of the southern Sky Atlas and its Equatorial Extension (together known as the SERC-J), as well as the Equatorial Red (ER), and the Second Epoch [red] Survey (SES) were all taken with the UK Schmidt.. The "Second Epoch Survey" of the southern sky was made by the Anglo-Australian Observatory (AAO) with the UK Schmidt Telescope.. Plates from this survey have been digitized and compressed by the ST ScI.. The digitized images are copyright © 1993-5 by the Anglo-Australian Observatory Board, and are distributed herein by agreement.. The "Equatorial Red Atlas" of the southern sky was made with the UK Schmidt Telescope.. The digitized images are copyright © 1992-5, jointly by the UK SERC/PPARC (Particle Physics and Astronomy Research Council, formerly Science and Engineering Research Council) and the Anglo-Australian Telescope Board, and are distributed herein by agreement.. The compressed files of the "Palomar Observatory - Space Telescope Science Institute Digital Sky Survey" of the northern sky, based on scans of the Second Palomar Sky Survey are copyright © 1993-1995 by the California Institute of Technology and are distributed herein by agreement..

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  • Title: Face-on map overview | Galaxy Map
    Descriptive info: Galaxy Map.. bb.. home.. what is this site about?.. Introduction.. Basic plan of the Milky Way.. Surveying the Galaxy.. Velocity.. Mapping hydrogen.. Face-on map overview.. Introduction to the Milky Way Explorer.. The Cloud Hunters.. The Star Sweepers.. Things Unseen: The Westerhout radio sources.. The Avedisova catalog: A real Hitchhiker s Guide to the Galaxy?.. Avedisova glossary.. Strange new worlds.. Hydrogen-alpha commentary.. Fragments.. User login.. Username:.. *.. Password:.. Request new password.. Home.. ».. This chapter describes the face-on maps of the Milky Way available from this site.. This is the view you would get if you were in a star ship hovering far above the galactic nucleus.. If you would like maps of the Milky Way as seen from the Earth, visit the.. Read first.. It is probably best to read the chapters on the.. and the techniques that astronomers use to.. survey the galaxy.. before looking at the detailed maps.. Some caveats.. The face-on maps on this site are based upon photometric and kinematic distance estimates taken from the scientific literature.. As explained in.. , photometric and kinematic estimates are often incorrect.. However, until recently, they were the only ones available for most of the galaxy.. Much more reliable distance estimates based on parallax are now becoming available and will make far more accurate maps possible over the next decade.. The current age of galactic exploration is perhaps similar to the period.. a few years after Columbus arrived in the "New World".. At that point most of the major continents were known by Europeans (although Australia and Antarctica were not) but maps of the world beyond Europe were incomplete and distorted.. In our case, the.. Gould Belt region.. within about 500 parsecs is fairly well known.. Beyond that: Here be dragons.. The maps on this site do not cover the full Milky Way.. Very little data is available on the half of the galaxy on the far side of the galactic nucleus, and even on our side of the galaxy, information on objects located more than about 10 thousand parsecs (about 30 thousand light-years) from the Sun is almost non-existent.. I've shown the area of the Milky Way covered by this site in the image on the right, which is derived from.. an artist's conception of the Milky Way released by NASA.. Even within 10 thousand parsecs, the face-on maps are incomplete in other ways.. The most obvious problem is a lack of molecular clouds for the fourth galactic quadrant.. No catalog of molecular clouds containing distance estimates has ever been published for this quadrant.. Molecular clouds are shown for the other galactic quadrants.. However, recent research has shown that the kinematic distance estimates given in the scientific literature for these clouds are often wildly inaccurate.. Beyond these clouds, most of the objects on the map are optically  ...   in 22 locations around our galactic region.. You can view these maps by clicking on the.. index image below.. These detail maps also show the main clouds of non-ionised atomic hydrogen gas in that region.. More on the maps.. The galaxy maps show the estimated distances of more than 5000 bright stars.. Even the dimmest of these is more than 1200 times brighter than our Sun, and the brightest of all are more than a million times brighter than the Sun.. The.. detail maps.. place yellow-green labels next to the great "beacon" stars with absolute bolometric magnitudes less than -9.. 5.. There are about 170 such stars in the Galaxy Map database and all of them are more than 600 thousand times brighter than our Sun.. The size of the star is relative to its bolometric magnitude (brightness) and the colour of the star is determined by its spectral type (temperature).. In addition to the brightest stars, the maps show the locations of all known star clusters with distance estimates.. As described in the.. Sources.. section, the maps also include nebulae from numerous databases.. All of these were originally believed to be.. HII regions.. , but subsequent research has shown than some are in fact supernova remnants, planetary nebulae, reflection nebulae, or more exotic objects.. Nebulae are shown as red spheres.. Also shown on the map are several thousand molecular clouds - vast cold regions of dust and gas that are the birth places of most stars.. Molecular clouds are shown as green spheres.. You can hover your mouse over each object on the maps (whether labeled or not) to get information about that object, and click on the object to see what additional information is available.. The NASA artist's conceptual image of the Milky Way is not intended to be accurate in any detail, and in fact overlaying the data from this site on the NASA image reveals many discrepancies as you can see in the image on the left (as well as in.. this more detailed image here.. ).. As just one example, the area of the very bright Cygnus X region appears as an inter-arm void on the NASA image.. Nevertheless, it gives a general sense of roughly where major objects on the map would appear on a traditional model of the Milky Way.. (If anyone reading this has the time and artistic skills to produce a revised version of the NASA conceptual image, I'd love to hear from you.. Please.. leave a comment on my blog.. Detail map index.. You can click the image map below to view any of the 22 detail maps.. How to use this map.. Map trivia.. What are all those pink clouds?.. Where are the spiral arms?.. ‹ Spiral structure and RCW 122.. up.. How to use this map ›..

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  • Title: Our Galactic Region | Galaxy Map
    Descriptive info: This is the beginning of a book about our region of the Milky Way galaxy (within about 10 thousand parsecs) to further document the.. galaxy map.. Introduction ›..

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  • Title: Kevin Jardine's blog | Galaxy Map
    Descriptive info: Blogs.. Kevin Jardine's blog.. Conclusions on mapping the Milky Way.. Submitted by Kevin Jardine on 7 June, 2013 - 14:26.. A few days ago I.. announced the Velocity Explorer.. , an interactive tool for exploring the velocity of gas in the galactic plane.. As part of that announcement I mentioned that I had used Velocity Explorer to create a model of the Milky Way:.. http://galaxymap.. org/drupal/node/202.. and even a partial map:.. org/drupal/node/204.. Maps derived from velocity data can't be treated very seriously for many reasons that essentially boil down to the fact that there is no straightforward relationship between velocity and distance.. A more reliable map will be possible only when many more maser parallax observations become available, especially from the southern hemisphere.. Nevertheless, I think I can derive several interesting conclusions from the exercise.. Of course since these conclusions are based on my (unreliable) map, they may be incorrect.. However, in most cases they don't depend upon a distance-velocity relationship and so may very well be real.. The spur system is elaborate.. shows many short bridges or "feathers" between the spiral arms.. This is not surprising as such structures are common in spiral galaxies.. What is a bit more unusual is the.. elaborate system of large spurs.. on the near side of the galaxy.. These include the Orion, Vela and Cygnet spurs as well as the Perseus bridge and at least four other structures.. This means that as maser parallax data becomes available the process of mapping objects located between the spiral arms will not be simple as we cannot assume that the masers are associated with one or two large spurs.. They will in fact be part of an elaborate hydrogen web.. The velocity data shows a double ring.. Instead of a simple ring (sometimes called the "near and far 3kpc arms"), surrounding the bar, the LAB velocity data clearly shows a more complex.. double ring structure.. It is not clear at this point how this maps into a physical structure but it seems unlikely that the bar is surrounded by a simple elliptical ring.. There is anomalous velocity in the anticentre too.. The Velocity Explorer shows at least.. two distinct bands of clouds.. with strongly negative velocities towards the outer galaxy.. There are major kinks in the Perseus and Sagittarius arms.. The velocity data as described in the section on.. the spiral arms.. suggests that the Perseus and Sagittarius arms are not simple logarithmic spirals but have more elaborate shapes.. In particular, a major bend in the Perseus arm between about 220 - 235 means that we are looking down rather than across the arm in this direction and will likely see an overdensity of spiral tracers.. There appears to be a large complex of clouds in the outer first quadrant.. There is a continuous velocity spread between the Norma and Centaurus arms from 37 to 47 as can be seen in.. this Velocity Explorer image.. I have labelled this region the.. Centaurus confluence.. on the.. It appears to be a region where the Milky Way's spiral structure breaks down and the Norma and Centaurus arms merge into a large flocculent cloud complex.. Login.. to post comments.. What is a spiral arm?.. Submitted by Kevin Jardine on 7 June, 2013 - 07:08.. Many galactic astronomers use the term "arm" in an inconsistent and confusing way.. As a good example, this.. image of the Milky Way on the Chandra website.. shows eight arms.. In a more recent example, this.. press release.. promotes the (in my view) ill-advised term "Local Arm" for the structure this website calls the "Orion Spur".. This confusion is becoming a greater problem as we get closer to the great dream of mapping the Milky Way.. For example, it is increasingly the case that the question "How many spiral arms does the Milky Way have?" has no clear answer not because we lack data, but because astronomers disagree over what an arm is, or use the term imprecisely.. So today I'm proposing a definition:.. A.. spiral arm.. is a large scale structure of atomic hydrogen that:.. lies outside the galactic centre region,.. is warmer and denser than its surroundings, and.. wraps around the galactic centre for more than 180.. In an astronomical context we can use the word "arm" as a short form of "spiral arm" when no confusion will result.. We should not use the word "arm" to refer to any other galactic structure than a "spiral arm".. The emphasis on atomic hydrogen makes sense to me because atomic hydrogen is the basic building block of all galaxies and including the reference to atomic hydrogen avoids arguments that a spiral arm is not an arm because it lacks other tracers like molecular gas, red giants or HII regions.. The definition precludes smaller structures that may exist in the galactic bar and the near and far 3kpc "arms" ("ring" or "ring structures" may be better terms for what has been called the 3kpc "arms").. By this definition, the evidence suggests that the Milky Way has four spiral arms.. Also by this definition the Orion Spur does not appear to be an arm.. Although it is a large structure, it is found (so far as we currently know) entirely or almost entirely on the near side of the galaxy.. The concept of.. spiral.. in a spiral arm implies that it wraps around the galactic centre and the Orion Spur does not appear to do this.. I also think that it is confusing in an astronomical context to use the term "arm" when we do not mean "spiral arm".. (Whether "Orion Spur" is an appropriate name for this structure is a different question which I'll address in a future blog post.. Announcing the Velocity Explorer.. Submitted by Kevin Jardine on 3 June, 2013 - 16:58.. About a year ago, the Harvard astronomer.. Thomas Dame.. suggested that I might consider experimenting with the 3D visualisation of velocity data.. As mentioned in the.. section of this site, in the 1950s there was tremendous excitement about the idea of using a rotational model of the Milky Way combined with velocity data to produce a map of the galaxy.. This effort ran into various problems and by the 1970s had been largely abandoned for a number of reasons, some scientific and some cultural (even astronomy has its fashions).. However, recently mapping the galaxy has come back into fashion, partly because of improved and new sources of data, and partly because increased computing power has made much more sophisticated data analysis possible.. Today I'm announcing the Velocity Explorer, an interactive tool for exploring gas velocity in the galactic plane.. The Velocity Explorer images were created using a marching cubes algorithm that is more typically used by medical researchers analysing MRI data to visualise tissue structures in the brain and other parts of the body.. It turns out that isosurfaces of constant gas temperature in the Milky Way are a bit like human tissue structures and can be analysed by similar tools.. There is a detailed introduction to the Velocity Explorer here:.. org/drupal/node/207.. I'm pretty sure that the Velocity Explorer is not really what Dame had in mind (I think he was more interested in rotating and otherwise manipulating individual cloud complexes).. However, it does fit closely with the overall goal of this site, which is to present research on mapping the Milky Way.. I've used the Velocity Explorer to derive a model for the Milky Way, described here:.. The model and map were fun to produce and the process I used to create them is described in detail, but they should not be treated too seriously.. The problems astronomers faced in the 1950s when using velocity data to map the galaxy are still around.. The only reliable way to map the galaxy is.. radio parallax.. Still, I think that the Velocity Explorer may be a useful tool for professional astronomers and may even suggest good parallax targets for radio astronomers.. And the.. new model of the galaxy.. described on this site might spark some interesting debate, which can only be good.. Patrick Moore and the future of UK astronomy.. Submitted by Kevin Jardine on 10 December, 2012 - 16:02.. Patrick Moore, the long serving host of the BBC's astronomy program.. The Sky at Night.. has died.. I don't remember hearing much about Moore when I lived in Canada,  ...   this site.. Colin Gum.. Submitted by Kevin Jardine on 23 January, 2012 - 09:05.. There are many astronomers who have contributed to our knowledge of the Milky Way over the past hundred years but for me one of the most fascinating is Colin Stanley Gum.. Gum is perhaps most famous for his discovery of the.. Gum Nebula.. , a vast expanse of nebulosity that may be the closest supernova remnant to our solar system.. The Gum nebula is just one of 85 nebular complexes catalogued in Gum's.. pioneering catalog.. of HII regions visible in the southern Milky Way.. Gum was also an early leader in the field of radio astronomy and his top rate mathematical skills played an important part in determining the exact location and orientation of the galactic plane and centre and in determining the current system of galactic coordinates.. For me, the most fascinating part of Gum's story was his persistence despite a lack of equipment and support from the management of the Stromlo observatory where he worked.. His thesis advisor, Clabon "Cla" Walter Allen, left for a new position at University of London Observatory, and the Stromlo director, Richard Woolley, had little interest in his work and at one point even attempted to reject his thesis and deny him a PhD.. If it had not been for the intervention of Ben Gascoigne as.. , Woolley might have succeeded in terminating the career of one of Australia's most prominent astronomers.. There are tiny details that suggest a dramatic story but these are mostly tantalising hints.. Gum reported that the nebular spectrograph originally used by Gum and Allen was.. destroyed by one of Stromlo's periodic forest fires.. , and he was forced to depend entirely upon tiny photographs from a 100 mm (4 inch) Schmidt camera salvaged from the flames.. Gascoigne mentioned that Gum "had to go into hospital for medical treatment" after he had written his thesis and there is a reference in a Stromlo history that this was because of a "nervous breakdown".. This is a rather vague term.. Perhaps it was clinical depression? In any case, Gum was able to recover from the incident and continue his career.. I came across some biographical details today that make Gum's story even more poignant: this.. genealogical data.. shows that Gum's father, Stanley Sturt Edgar Gum, died the year his son was born.. Curiously, I have not been able to find a single photograph of Colin Gum on the Internet, but since his father served in the Australian infantry during the first World War, Stanley Sturt Edgar Gum's portrait.. can be found here.. I wish that someone would write the biography of Colin Gum that he so richly deserves.. I think that his enormous achievements despite immense obstacles would be a great inspiration for many young scientists today.. An important part of a Gum biography would be his relationships with the two Stromlo directors during his all-too-short career: Richard Woolley and Bart Bok.. Richard van der Riet Woolley.. was best known for his sarcastic sense of humour and his sometimes spectacularly bad scientific and technical judgement.. In 1947,.. when asked.. where he thought radio astronomy would be in 10 years, his response was "forgotten".. He also remarked that the idea of space travel was "utter bilge" and wrote that "The whole procedure [of shooting rockets into space].. presents difficulties of so fundamental a nature, that we are forced to dismiss the notion as essentially impracticable".. It is odd that.. Bart Bok.. asked Gum's younger colleague.. Alex Rodgers.. to lead the effort to create an expanded version of Gum's catalogue, which became the.. RCW catalogue.. Gum's equivalent in the northern hemisphere, Stewart Sharpless, produced an expanded version of his own original catalogue.. Why was Gum not asked to do the same? Perhaps Gum himself wanted to move on to other projects? Certainly Bok's respect for Gum's scientific credentials seems clear from Bok's moving.. obituary for Gum.. , published after Gum's tragic death in a Swiss skiing accident in 1960.. Cygnus X image.. Submitted by Kevin Jardine on 11 January, 2012 - 08:25.. As part of the annual meeting of the American Astronomical Society, NASA released today the most detailed ever.. infrared image.. of the Cygnus X region.. The mysterious.. Cygnus X.. region is the closest major star formation region to our solar system.. It dwarfs the more local star formation regions in the.. Gould Belt.. such as Sco OB2 and the Orion molecular clouds.. At visual frequencies Cygnus X is obscured by the Rift dust clouds.. It was originally detected at radio frequencies and now a team led by Harvard astronomer.. Joseph Hora.. has revealed its full glory using infrared images from the Spitzer space telescope.. Hora tells me that astronomer-illustrator.. Robert Hurt.. helped to create the image.. It is based on data collected before Spitzer ran out of coolant and combines four infrared frequencies.. Up to this point, the most detailed Cygnus X image available was.. this one from MSX.. (the Spitzer image is rotated roughly 90 degrees to the MSX image).. I'll add the new Spitzer image to the.. in the near future.. I.. blogged about the distance to Cygnus X.. in November 2010 and noted that there was a controversy about whether the objects in this direction are really part of a single region.. recent paper.. uses radio parallax measurements to establish that there is indeed a single major star formation region in this direction and like our own Gould Belt, it is part of the.. Orion spur.. The infrared image is centered upon the compact starburst cluster and OB association.. Cyg OB2.. , which has created a huge bubble in the interstellar medium.. The radio parallax study shows that many other objects in this direction and at a similar distance have motions different from the expanding bubble surrounding Cyg OB2 and so probably developed independently from Cyg OB2 within the same gigantic molecular cloud.. Kepler-22b map poster.. Submitted by Kevin Jardine on 8 December, 2011 - 08:04.. Hundreds of new visitors have arrived at Galaxy Map over the past few days looking for a map showing the location of the newly discovered Earth-like planet.. Kepler-22b.. and its G5V class parent star.. Kepler-22.. I've never seen this kind of response to a news story before - usually traffic spikes are caused by other sites like Astronomy Picture of the Day linking to Galaxy Map.. In this case the traffic spike has come from hundreds of people independently searching for a map.. To meet the demand, I've created a poster derived from several Galaxy Map resources.. The poster is here:.. org/kepler22b/poster.. png.. The poster is based on these resources:.. Interactive map of the Gould Belt region:.. org/detail_maps/gould.. html.. Basic plan of the Milky Way:.. org/drupal/node/171.. Milky Way Explorer:.. org/drupal/node/127.. On the Gould Belt region map, red balls are HII regions of ionised molecular hydrogen gas, green balls are dusty molecular clouds, orange circles are star clusters and the small dots are extremely bright stars (typically supergiants or O and B class hot stars).. First WISE image.. Submitted by Kevin Jardine on 17 April, 2011 - 10:39.. Below is an image of Sh 2-284 I made this morning from the WISE data.. The speed of the image server is now reasonably fast - I think the problem yesterday was just that it was down for a while.. I used all four channels, using the equations:.. red = w4.. green = 0.. 25*w2+0.. 75*w3.. blue = 0.. 75*w1.. with a bit of preprocessing of the individual channel FITS files using Aladin first.. I've rotated the image to the right by 90 to compare it with an earlier image I made using Spitzer IRAC and SuperCOSMOS data.. Here's the WISE image:.. (.. A much larger 4095x4095 version can be downloaded by clicking here.. and here's the.. earlier Spitzer/SuperCOSMOS image.. for comparison:.. The two obvious differences are that:.. the Spitzer data is higher resolution.. the WISE data reveals more at longer (redder) wavelengths than Spitzer's IRAC instrument.. (Spitzer's separate MIPS instrument also covers the longer wavelengths).. For this reason the WISE image shows more structure in the interior of Sh 2-284 than IRAC.. It looks like the WISE image server is going to be very useful and I'm looking forward to making more images!.. 1.. 2.. 3.. 4.. 5.. 6.. 7.. 8.. 9.. next ›.. last »..

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  • Title: Gallery
    Descriptive info: Gallery.. Previous.. Next.. glossary.. You can use the Previous and Next links underneath the gallery to view more images.. Click on a thumbnail to see a larger image.. From there, you can return to the gallery, go to a description of the object or see the location of the object on the map.. These images were created using the POSS-II/UKSTU data of the.. SuperCOSMOS.. According to my correspondence with the Royal Observatory Edinburgh and the Space Telescope  ...   non-commercial purposes so long as I include this fine print for the SuperCOSMOS data:.. Use of these images is courtesy of the UK Schmidt Telescope (copyright in which is owned by the Particle Physics and Astronomy Research Council of the UK and the Anglo-Australian Telescope Board) and the Southern Sky Survey as created by the SuperCOSMOS measuring machine and are reproduced here with permission from the Royal Observatory Edinburgh.. and this acknowledgement taken from the DSS site:..

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  • Title: Send A WebCard
    Descriptive info: Send a Galaxy Card.. Pick up a Galaxy Card.. Forgotten your pickup code?.. Visit Galaxy Map website.. Choose an image below and send a Galaxy Card.. Send your friends some of these beautiful nebula images and help spread the word about the.. Galaxy Map website.. These images were created  ...   the Galaxy Map nebula gallery for.. full details and copyright information.. Pages:.. next.. Currently browsing: All Categories.. RCW 40.. RCW 41.. RCW 45.. RCW 36.. RCW 38.. RCW 35.. RCW 49.. NGC 3603 (RCW 57B).. NGC 3576 (RCW 57A).. RCW 58.. RCW 32.. RCW 20.. Powered by.. WebCards.. v1.. 0..

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  • Title: Sources | Galaxy Map
    Descriptive info: This chapter describes the sources for the.. face-on maps of the Milky Way.. available on this site.. For the sources for the Milky Way Explorer (the Earth-centred maps), see the.. Milky Way Explorer introduction.. Every one of the 8978 objects currently on the face-on Milky Way maps has a position, distance, and either size or luminosity determined from the scientific literature.. At the fourth zoom level, clicking on an object shows the distance in parsecs, the position in galactic longitude and latitude and the source of the data (and may show.. more.. depending on the object).. You can download the basic map data (including distances, positions and sources) as an.. Excel spreadsheet.. You can also download.. more detailed data on the stars here.. (Most of the time the star class data is split into separate spectrum and luminosity columns, but not always.. Stars.. The major sources of the star data are the ".. Catalog of Luminous Stars in Associations.. " and the ".. Clusters Catalog of Luminous and Early-Type Stars in the Field.. ".. These catalogs were released by Roberta Humphreys, Cynthia Anne Blaha and Douglas McElroy in 1984 and are based in part on Roberta Humphreys' original luminous star catalog, published in ".. Studies of luminous stars in nearby galaxies.. I.. Supergiants and O stars in the Milky Way.. " in 1978.. Oddly, none of these catalogs are available from the VizieR depository of astronomical catalogs, but the first two can be downloaded from.. NASA.. The "Catalog of Luminous Stars in Associations" does not provide explicit distances for each star, but instead lists the OB association the star is part of.. An additional table provides size and distance estimates for these associations.. Simply mapping all the stars that belong to an association at the estimated distance of the association would force them all unrealistically into a narrow arc.. To avoid this, I have randomly perturbed the distances of these association stars, however keeping them within the estimated borders of their association (assuming that the stars for each association fall within the boundary of a circle in the galactic plane).. In some cases, however, a cluster of these stars are indeed concentrated in the association and these can be seen on the map as a line of stars with identical longitude and latitude coordinates.. This information has been supplemented by van der Hucht's ".. The Seventh Catalogue of Galactic Wolf-Rayet stars.. ", published in 2001, and ".. The distribution of bright OB stars in the Canis Major-Puppis-Vela region of the Milky Way.. ", published by Kaltcheva and Hilditch in 2000.. The colour of each star as displayed on the galaxy map depends on its spectral type (essentially its temperature).. The O-stars are purple, B-stars are blue, A are white, F are yellow-white, G are yellow, K are orange and M are red.. Wolf-Rayet stars are pink.. The size of the star is determined by its absolute bolometric magnitude.. In most cases this was supplied in the catalog.. For Wolf-Rayet stars I have applied a bolometric correction of 4.. 5 as suggested by Smith and Maeder in ".. The bolometric corrections and the M(dot):L relation for Wolf-Rayet stars.. " in 1985.. The dimmest star on the map has a bolometric magnitude of -2.. 93, which is about 1200 times brighter than our Sun.. The brightest stars on the map are about one million times brighter than our Sun.. Molecular Clouds.. The ordinary matter in the Milky Way galaxy is dominated by large clouds of hydrogen gas.. One form of this gas, called atomic hydrogen, consists of a proton orbited by at most one electron.. Large clouds of atomic hydrogen gas are called HI regions and can be detected in the radio frequencies around 1420 MHz.. The first major exploration of the entire Milky Way galaxy accessible from the northern hemisphere was carried out by.. Gart Westerhout.. using the Dwingeloo radio telescope (set up near a Dutch national park) in the 1950s.. Westerhout published his famous paper ".. A survey of the continuous radiation from the Galactic System at a frequency of 1390 Mc/s.. " in 1958.. Westerhout identified 81 major sources of galactic radiation at this frequency.. Many of these are now known to be major areas of star formation and are still referenced by their Westerhout numbers (eg.. W51).. Hydrogen gas also comes in the form of two hydrogen atoms bound together to form a molecule.. Molecular hydrogen is extremely difficult to detect directly.. Fortunately, molecular hydrogen clouds often contain molecules of  ...   many clouds are assigned the same distance.. To better display these clouds, I have randomly perturbed these distances within the range of +/- 25 parsecs.. I have included all the clouds with defined distances in the catalogs except in the case of the huge catalog of more than 10 thousand clouds associated with "The Equilibrium State of Molecular Regions in the Outer Galaxy".. In this case, the authors of the paper warn that clouds with velocity >= - 20 km/s have highly inaccurate distances because they are close and may be affected by localised gas streaming.. I only included clouds with velocity -20 km/s.. As this selection also contains very faint clouds, I added an additional restriction to clouds with total luminosity > 270 K km pc2/s.. According to the paper, these clouds contain 90 percent of the total luminosity.. These two restrictions reduce the size of the catalog to about 625 clouds and I have placed these on the map.. Molecular clouds are shown as translucent green spheres.. Extremely hot stars (O-stars, Wolf-Rayet stars or hot B-stars) ionize the hydrogen gas in any clouds surrounding them, stripping electrons away from the proton nucleus and causing the gas to glow a dull red.. Even more importantly, these HII regions also emit characteristic radio waves, making them detectable even on the opposite side of the galaxy.. Stewart Sharpless published ".. A Catalogue of H II Regions.. " in 1959.. This included 313 regions (called Sh 2 regions) visible from the northern hemisphere.. Sharpless did not provide distance estimates, but in 1982, Blitz, Fich, and Stark analyzed carbon monoxide clouds that appeared to be associated with the Sharpless HII regions and added 62 new BFS regions of their own in ".. Catalog of CO radial velocities toward galactic H II regions.. They were able to provide distance estimates for many of these regions and I have included these in the map.. Sharpless's catalog was soon matched by a southern hemisphere version listing 182 HII regions based on data from Australia's Mount Stromlo observatory.. Rodgers, Campbell, and Whiteoak published ".. A catalogue of H-alpha-emission regions in the southern Milky Way.. " in 1960.. These are called RCW regions.. Numerous studies have been done since that estimated the distances of one or sometimes a few RCW regions, but there has been no systematic attempt to determine distances to all HII regions visible from the southern hemisphere until recently.. More information on the creation of the Sharpless, RCW and related catalogs can be.. found here.. Over the last few years, studies appeared that attempted to derive distances for a large number of Milky Way objects.. In 2003, Delphine Russeil published ".. Star-forming complexes and the spiral structure of our Galaxy.. and Roberta Paladini along with many colleagues published ".. A radio catalog of Galactic HII regions for applications from decimeter to millimeter wavelengths.. " of 1442 HII regions derived from 24 previous catalogs.. Although the Paladini et.. al.. "master catalog" of HII regions did not itself include distance estimates, in 2004, Paladini, Davies, and DeZotti published a paper, ".. Spatial distribution of Galactic HII regions.. " describing the techniques they used to derive distance estimates for more than 500 HII regions.. In 2005, Roberta Paladini was kind enough to send me a.. personal communication.. with these estimates and I have placed these objects on the galaxy map.. HII regions are shown as red spheres.. Star clusters.. Unlike the other object types, data on optically visible star clusters has long been centrally catalogued.. Gosta Lynga began a catalog of all optically visible star clusters in 1977 (".. Plans for a Computer-Readable Cluster Catalogue.. ") and it has since been continued by others, most recently in the ".. New catalogue of optically visible open clusters and candidates.. " by Dias, Alessi, Moitinho, and Lépine.. This catalog continues to be updated and the.. latest version is available here.. The galaxy map includes all the star clusters with defined distances from version 2.. 7 of the Diaz et.. cluster database (27 October 2006).. In addition to optically visible star clusters, there are now several hundred optically invisible star clusters known from infrared observations.. (For example, see ".. New infrared star clusters in the Northern and Equatorial Milky Way with 2MASS.. ) Infrared star clusters will be added to a future version of the galaxy map where distance estimates are available.. Optically visible star clusters are shown as gold circles.. ‹ Where are the spiral arms?.. Introduction to the Milky Way Explorer ›..

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  • Title: Basic plan of the Milky Way | Galaxy Map
    Descriptive info: Robert Hurt's famous.. diagram of the Milky Way.. (Rotated for this site by.. engrafi.. ).. It is easy to drown in the details of any map, so it is useful to start with a basic plan of the Milky Way.. Those who want a more detailed (although less complete) map can visit the.. One of the best (and surely the prettiest) basic plan illustrations currently available was created by the NASA astronomer-artist.. and released in 2008.. Hurt's illustration was created to.. highlight scientific conclusions.. on the inner galaxy from a team of astronomers led by.. Robert Benjamin.. and associated with the.. Spitzer infrared space telescope.. However, there are so few well done images of the Milky Way available that the illustration has been widely used in scientific papers, even by researchers who vehemently disagree with some of the Spitzer team's basic conclusions.. I've.. blogged about some problems with the Hurt illustration.. , including details in the Orion spur and outer galaxy.. Fortunately there are other illustrations available that correct these problems and I'll mention one below.. Orientation.. One other problem with the original Hurt illustration is that it is upside down.. The standard orientation for Milky Way face-on maps in scientific publications (and this site) has 0 galactic longitude (the direction to the galactic nucleus) facing downwards.. Hurt's illustration has it facing upwards.. There is nothing scientifically invalid about this orientation (it is completely arbitrary) but it is still rather confusing.. It's a bit like a map of the world with Antarctica at the top.. This has some novelty value but is probably not the best orientation to use for general education.. So the version I'm using is rotated into the standard view.. Spiral arms.. Hurt's illustration shows a barred spiral galaxy with two major arms.. Even this basic design is controversial because many astronomers argue that the Milky Way has four major arms.. Hurt has put the other arms into his illustration as well but deemphasised them.. This.. Chandra image.. shows the hot x-ray halo surrounding the massive spiral galaxy NGC 5746.. It also shows an optical view of the galaxy including the central bulge and thin disk.. The Milky Way has a similar basic structure if viewed edge-on.. Unfortunately astronomers agree on the name of only one of these arms.. This is called the Perseus arm and was discovered in the 1950s.. It is the spiral arm that one sees first when looking into the outer galaxy (180 ).. As one might expect, it is most obvious at visual frequencies from the Earth in the direction of the constellations Perseus and Cassiopeia.. The other arms have been treated a bit like those roads in European cities that change their names every few blocks.. The other major arm in Hurt's illustration runs through the southern constellations Scutum, Crux and Centaurus (among others) as viewed from Earth so in the scientific literature it can be called the Scutum-Crux arm, the Scutum-Centaurus arm, the Crux-Centaurus arm, the Crux-Scutum arm, the Scutum arm, the Crux arm, the Centaurus arm, and even the Scutum-Crux-Centaurus arm.. As Centaurus is by far the largest of the three constellations, I strongly favour the use of the term "Centaurus arm" and try to use that name as much as possible in this website.. Many astronomers believe that the Milky Way has four major spiral arms and this is certainly what appears in the atomic hydrogen data as I describe in the.. chapter on kinematic distance estimates.. Others argue that the third and fourth "arms" consist of a few discontinuous active segments and are not full spiral arms in the same sense as the Perseus and Centaurus arms.. Some argue that the number of arms depends upon the frequency of light and the type of objects.. For example, the Spitzer infrared astronomers favour a two major arm model because red giant stars (which emit a lot of infrared) are largely confined to the Perseus and Centaurus arms, whereas radio astronomers tend to favour a four major arm model because radio telescopes can detect atomic hydrogen in all four arms.. Some references for this debate are supplied in my.. Four arms vs.. two.. blog entry.. In any case, it is still possible to give the third and fourth arms names and describe their positions.. More data is required to determine if they are as fully developed as the Perseus and Centaurus arms.. The third arm can be seen in the direction of the constellations Sagittarius and Carina (and so is sometimes called the Sagittarius arm,  ...   and Delta quadrants of the.. Star Trek mythos.. , the first, second, third and fourth galactic quadrants are centred on the Sun rather than the galactic nucleus.. This is less aesthetically pleasing but more practical scientifically as almost nothing is known about objects on the far side of the galactic nucleus.. The bar.. The central bar has a thicker bulge made up of mostly older stars.. The bar of the Milky Way is tightly wrapped by two additional spiral arms.. These are called the near and far 3kpc arms.. (This is short for 3000 parsecs because these arms are located approximately 3000 parsecs from the centre of the galaxy.. ) Note that the 3kpc arms are distinct from the 4 arms I mentioned in the spiral arms section above.. The bar itself has a complex structure including an inner bar, a molecular hydrogen ring, two miniature bar spiral arms (internal to the bar and distinct from the 3kpc arms), a central molecular zone and at the heart of the galaxy, the 4 million solar mass black hole Sgr A*.. You can read this.. 2009 paper.. to find out more about the galactic bar and the 3kpc arms.. The halo.. The Milky Way (like other spiral galaxies) is surrounded by a large halo region which contains globular clusters, large clouds of hydrogen gas, and a huge mass of the mysterious dark matter.. This detailed image shows the major known components of the Orion spur and the location of the Sun (yellow dot).. Our Sun is located within the Orion spur.. Although not a spiral arm, the Orion spur is nevertheless a major Milky Way structure that crosses the Perseus arm, linking the Sagittarius and Outer arms.. Such spurs connecting two or more spiral arms are a common feature of spiral galaxies.. The Orion spur is sometimes confusingly called the Orion arm or the Local arm in scientific papers.. I will try to avoid that confusion in this website.. The Hurt illustration does not represent the Orion spur very accurately and so instead I am using an image created by scientific illustrator.. that better represents the region of the Milky Way close to the Sun.. The Orion spur appears to branch off from the Sagittarius arm at or near the intense radio source W51, which is a large complex of star formation regions and supernova remnants.. It continues through the Cygnus X complex of star formation regions, which includes Cyg OB2, one of the most luminous OB associations known in the local group of galaxies.. It passes through the Rift dust clouds and into an expanding ring of bright star formation regions called the Gould belt.. The Gould belt includes the Orion molecular cloud and our own Sun (which is much older than the Gould belt and is just passing through).. The Gum nebula supernova remnant dominates the Orion spur just past the Gould belt.. Beyond the Gum nebula, the spur forks.. The main branch transits the Perseus arm in the direction of the constellation Canis Major and terminates in or near the Outer arm.. A smaller branch forms the complex of molecular clouds and star formation regions called the Vela Molecular Ridge.. Perhaps not surprisingly, the scientifically most controversial bits of this description of the Orion spur are in regard to its ends.. The Russian astronomer Veta Avedisova tentatively suggested an origin in W51 in a.. 1985 paper.. which states: "W51 may well belong to the local arm.. One also cannot rule out that the main arm might split somewhere in the vicinity of W51".. This view is also supported by a.. 2010 paper.. , which more specifically gives the origin as the infrared source.. W51 IRS2.. On the other hand, a.. 2008 paper.. argues for a closer origin for the Orion spur in the vicinity of the infrared source G59.. 7+0.. 1 (IRAS 19410+2336), which is associated with the star cluster NGC 6823 and the nebula Sh 2-86.. (This spectacular object has been imaged by both the.. Spitzer.. Herschel.. infrared space telescopes.. The author lists of the 2008 and 2010 papers referenced in the last two paragraphs overlap, suggesting that either these authors disagree amongst themselves or that opinion has shifted back towards a W51 origin for the Orion spur in the later paper.. The Perseus transit at the other end of the Orion spur is described in a.. major 2008 survey paper.. on the structure of the Milky Way in the third quadrant.. ‹ How did this site come to be?.. Surveying the Galaxy ›..

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  • Title: Our Galactic Region | Galaxy Map
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  • Title: Kevin Jardine's blog | Galaxy Map
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  • Title: Introduction to the Milky Way Explorer | Galaxy Map
    Descriptive info: This IRAS infrared image from the.. shows the expanding ring of clouds surrounding Lambda Orionis.. Betelgeuse is visible as the bright white star just to the upper left of the ring.. You can find the.. Milky Way Explorer here.. , but you may wish to read this introduction before using it.. This chapter describes the Milky Way Explorer, a set of multiwavelength maps of our galaxy as seen from the Earth.. If you would like maps of the Milky Way as seen from a star ship hovering far above the galactic nucleus, visit the.. Seeing through the dust.. Perhaps the most difficult problem in mapping the Milky Way galaxy is that our view of much of it is blocked by large clouds of dust.. As a result, the standard lists of visible nebulae and intensely luminous stars are sadly incomplete.. The Milky Way Explorer is intended to help solve this problem by combining images and data from outside the visual spectrum to produce a new view of our home galaxy.. These non-visual frequencies are transmitted through the Milky Way's dust clouds and enable us to see what lies beyond them.. Major data sets.. The Milky Way Explorer combines three major infrared surveys:.. MSX.. , along with lower resolution images at radio, microwave and hydrogen-alpha frequencies.. Overlaid on this data are markers showing the locations of the star formation regions listed in the.. Catalog of Star-Forming Regions in the Galaxy.. , produced by Veta Avedisova and her colleagues at the Centre for Astronomical Data in Moscow, as well as the supernova remnants from Dave Green's.. Catalogue of Galactic Supernova Remnants.. One of the hydrogen-alpha images in addition contains detailed information from several data sources on ionising stars.. The full sources of the data used to create the Explorer are described in the Sources section at the bottom of this page.. The MSX data are currently the most detailed complete images of the galactic plane available outside the visual spectrum.. The Spitzer data are still more detailed but cover only the inner galactic plane.. The lower resolution IRAS data cover almost the entire sky.. The Avedisova catalog is the most comprehensive list of star forming regions (including regions not detectable in visual light) with 3229 major regions, and a total of 66885 observations referenced.. The data sets work well together, with the Avedisova catalog forming a guide to many of the major objects visible at infrared and other frequencies.. Explorer development.. In June 2007, I (.. Kevin Jardine.. , the creator of this site), downloaded the complete A-band (8.. 28 μm) MSX dataset and used it to produce a single large colour map of the galactic plane.. Like many astronomical images, the MSX A-band measures the intensity of a single frequency of radiation.. Compressing this data into 256 shades of gray would lose most of the detail in the data, so I created a 24-bit false colour scheme designed to show off as much of the detail in the data as possible.. The complete MSX dataset forms a 216000 x 5998 pixel image.. As this image is obviously too large to view at once, I.. originally created a Flash application.. to view the data at two levels of resolution - the full resolution and one reduced to a tenth of the size in height and width (that is, a 21600x600 pixel image).. In June 2008, NASA released the stunning.. Spitzer mosaic of the inner galactic plane.. This was available in several formats but the one that caught my attention was a.. Google Maps.. interface.. This offered a full screen interface that loaded much more quickly than my original Flash application.. Between September and November 2008, I converted my application to the Google Maps interface and added IRAS and radio data and well as more comprehensive versions of the hydrogen-alpha and microwave data included in my original application.. I also took advantage of the Google Maps interface to make accessing the star formation region and supernova remnant information much easier.. All of the map tiles (including the ones NASA created for the Spitzer map as well as my own) were created using the very useful.. Google Map Image Cutter.. Using the Milky Way Explorer.. Unlike the.. face-on map of the Milky Way.. also available from this site, the Milky Way Explorer shows the sky as we would see it from Earth, albeit with eyes that could detect infrared, radio and microwave frequencies.. By default, the Explorer shows an infrared IRAS image centred on the Milky Way's nucleus.. You can then pan and zoom from this using the familiar Google Maps interface.. Two sets of coordinates identify your location.. The first row  ...   the Explorer, you can download any of the 21600x600 galactic plane images below for off-line viewing.. On Windows, you would do this by right-clicking on the image and selecting "Save link as.. ".. You can also view the images directly in your browser by clicking on the image (although viewing images this large may crash some browsers.. MSX 8μm infrared.. Radio.. Microwave.. Hydrogen-alpha.. Composite of radio, infrared and hydrogen-alpha.. Images.. The IRAS colour composite images were created by combining all four IRAS frequencies (12μm - violet, 25μm - cyan, 60μm - green, 100μm - red).. The data is taken from the.. IRIS - Improved Reprocessing of the IRAS Survey.. site and reprojected to the galactic cartesian projection used for all the Milky Way Explorer maps.. As the IRIS site mentions, there are a few artifacts in the data, including some holes, inconsistent data from overlapping images taken at different times, and zodiacal dust visible from our local solar system.. The MSX infrared data is described.. here.. and the complete set of FITS data can be.. downloaded here.. The Spitzer data is a composite of several infrared bands from two Spitzer Space Telescope surveys, MIPSGAL and GLIMPSE, of the inner galactic plane, as.. explained in more detail here.. The Effelsberg/Parkes radio data is from two separate sources.. I started with the Effelsberg 11 cm (2.. 7 GHz) data from.. and supplemented it with the lower resolution Parkes 2.. 4 GHz data from.. Because the Parkes data is lower resolution and has a somewhat different frequency, there are obvious transition points in the radio map.. There does not appear to be a complete galactic plane radio map at the Effelsberg resolution or better, so this somewhat awkward compromise will have to do for now.. The LAB HI data is derived from the.. Leiden/Argentine/Bonn galactic HI survey.. and was created from a velocity integrated (-250 km/s v 250 km/s) FITS file kindly supplied to me by.. Tom Dame.. from the.. Harvard-Smithsonian Center for Astrophysics.. The microwave data is from the FITS file available from the.. Milky Way in Molecular Clouds.. page.. The Cassiopeia A supernova remnant and nearby nebulae in the direction of the Cas OB2 association, at radio frequency.. The hydrogen-alpha data is from the highest resolution data available from Douglas Finkbeiner's all-sky hydrogen-alpha page.. The radio, microwave, hydrogen-alpha and MSX images were constructed from the single frequency data using 24-bit colour schemes of my own devising in which the hue shifts from a dark blue to a light red with the emission intensity.. An exception is the LAB HI image which uses a more hue-restricted temperature colour scheme that seemed to best bring out the details of many of the huge HI clouds.. The SuperCOSMOS data used to create the.. SuperCOSMOS Explorer.. is taken from the.. blocked-down SuperCOSMOS data.. (1/16 the width and height of the full AAO/UKST H-alpha survey), then reprojected to galactic coordinates and mosaicked together using.. Skyview-in-a-jar.. I've rendered this as black and white as this seems to best reveal the subtle fine details in the original images.. The SuperCOSMOS data is not calibrated.. I've used the constant median offset de-edger from Skyview-in-a-jar to reduce some of the abrupt plate transitions, but they are still visible.. I've tried other mosaicking packages like.. Swarp.. but they have not improved the mosaic significantly.. Some of the difficulties involved in calibrating this data are.. described on the SuperCOSMOS site.. Overlays.. Veta Avedisova's Catalog of Star-Forming Regions in the Galaxy can be downloaded from Vizier.. The supernova remnants were taken from the catalog on.. Dave Green's.. website.. The ionising star data were taken from Cameron Reed's.. Catalog of Galactic OB Stars.. (the version dated 24 July 2007).. This is much more current than the 1984 Blaha and Humphreys data used to construct the face-on map of the galaxy elsewhere on this website.. The Reed data lacks distance estimates but these were not necessary for the Milky Way Explorer.. The Reed data is quite hard to find and can only be downloaded one file at a time.. The five files are.. obcatalog.. dat.. obubvbeta.. ob4color.. obmk.. obnotes.. doc.. The ionising star cluster data were taken from Nina Kharchenko's.. star cluster catalog.. and the related.. new cluster catalog.. I selected the 143 clusters which had at least one ionising star (Wolf-Rayet, O-star or B star hotter than B3) as a probable member.. The OB association boundaries are taken from the.. Blaha-Humphreys luminous star catalog.. Thank you!.. Thanks for reading this introduction.. You can find the actual.. If you enjoy using it or have questions or suggestions for improvements, you can email me at kevinjardine (at) yahoo.. com.. ‹ Sources.. The Cloud Hunters ›..

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